Airplay not consistently working on MacBook Pro to Apple TV

Tech Details: MacBook Pro (Early 2015, 13" OS X El Capitan 10.11.6); Apple TV (4th Gen. OS 9.2.2)

My Airplay is not consistently working on my MacBook Pro and despite hours yesterday online with Apple Support (both a Mac advisor and then a wireless advisor) we could find nothing that made sense. Here is what IS working: IPAD Air2 and IPhone 6 have no problems with Airplay. In addition, I have 3 User IDs setup on my MacBook and the two (one a test that we tried yesterday and one that my grandchild uses) and all but mine are able to Airplay. When I am logged in under either of those IDs I have the full option to arrange displays (Display Preferences) and also have the mirroring options available when clicking on the Airplay icon.

This is what I do not understand; only my ID (administrator) does not have the three screens for System Preferences > Display preferences and I do not have any mirroring options association with Airplay. The click box to mirror is available on the Display Preferences screen but by clicking it and then selecting the Apple TV I get the same error message that cannot connect to Apple TV. Between Apple support and me I have tried every possible troubleshooting step and we cannot figure this out. It must have something to do with my user ID settings if the other two user IDs can airplay, right? In addition, when I am trying to connect (with my ID) to Apple TV it asks for the verification code (that one can enable on Apple TV in Airplay Settings) even though I do not have that enabled. In System Report>Hardware>Graphics/Displays I note that the Intel Graphics 6100 Color LCD (default) has the mirror marked OFF. I do not know if this is significant.

What I do know is that I have been through every setting I can think of in wireless, hardware, displays, Apple TV, and along with the additional assistance of Apple I do not understand what else I can change. I also turned my firewall off and deleted all safari extensions. Any issue with just creating a new Admin user ID for a workaround? Thank you.